You can use redsn0w to jailbreak any iPhone or iPod Touch using Mac, Windows, or Linux. For both 3.0 and 3.0.1 firmwares, you should point redsn0w at the 3.0 IPSW. If you see it hang at Ã¢â‚¬Å“waiting for rebootÃ¢â‚¬Â, just unplug and replug that USB cable.

You can use ultrasn0w to unlock the iPhone 3G/3GS, or BootNeuter to unlock the iPhone 2G. Both ultrasn0w and BootNeuter are available via Cydia.

You can use PwnageTool for Mac to create custom IPSWs with pre-installed packages.